Conference PapersCopyright (c) 2018 Dublin Institute of Technology All rights reserved.https://arrow.dit.ie/engschmeccon
Recent documents in Conference Papersen-usSat, 06 Jan 2018 02:02:00 PST3600Mitigation and Control of the Overcuring Effect in Mask Projection Micro-Stereolithographyhttps://arrow.dit.ie/engschmeccon/74
https://arrow.dit.ie/engschmeccon/74Thu, 04 Jan 2018 02:40:30 PST
Mask Projection micro-Stereolithography (MPμSL) is an additive manufacturing technique capable of producing solid parts with micron-scale resolution from a vat of photocurable liquid polymer resin. Although the physical mechanism remains the same, the process differs from traditional laser-galvanometer based stereolithography (SL) in its use of a dynamic mask UV projector, or digital light processor (DLP), which cures each location within each 3D layer at the same time. One area where MPµSL has garnered considerable attention is in the field of microfluidics and Lab-on-a-Chip, where complex multistep microfabrication techniques adopted from the semiconductor industry are still widely used, and where MPµSL offers the ability to fabricate completely encapsulated fluidic channels in a single step and at low cost [1–3]. However, a significant obstacle exists in the prevention of channel blockage due to overcuring of the polymer resin [4, 5]. Overcuring can be attributed to the so-called ‘back side effect’ [2] which occurs during the build process as light from successive layers penetrates into the resin to a depth greater than the layer thickness. This effect is most prevalent in channels or features oriented horizontally (in a parallel plane to that of the build platform). Currently there are two main approaches in controlling the cure depth; 1. the chemical approach, which involves doping the resin material with a chemical light absorber [6–8]; and 2. by improving the system's hardware and optical elements to improve the homogeneity of the light dosage and control the cure depth [9]. Here we investigate a third approach through modification of the 3D CAD file prior to printing to mitigate for UV light leakage from successive build layers. Although used here in conjunction with the MPμSL technique, this approach can be applied to a range of SL techniques to improve printer resolution and enable production of internal features with higher dimensional accuracy.
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Nigel Kent et al.Mathematical Modelling of a Low Approach Evaporative Cooling Process for Space Cooling in Buildingshttps://arrow.dit.ie/engschmeccon/73
https://arrow.dit.ie/engschmeccon/73Mon, 13 Feb 2017 02:46:08 PST
This paper describes a mathematical model of a low approach open evaporative cooling tower for the production of high temperature indirect cooling water (14-16°C) for use in building radiant cooling and displacement ventilation systems. There are several potential approaches to model evaporative cooling, including: the Poppe method, the Merkel method and the effectiveness-NTU (ε-NTU) method. A common assumption, applied to the Merkel and ε-NTU methods, is that the effect of change in tower water mass flow rate due to evaporation is ignored, which results in a simpler model with reduced computational requirements, but with somewhat decreasedaccuracy. In this paper, a new improved method, called the corrected ε-NTU approach is proposed, where the water loss due to evaporation is taken into account. It is expected by this correction the results of improved ε-NTU in the category of heat transfer will be more close to the results ofmore rigorous Poppe method.The current mathematical model is evaluated against experimental data reported for anumber of open tower configurations, subject to different water temperature and ambient boundary conditions. It is shown that the discrepancies between the calculated and experimental tower outlet temperatures are to within ±0.35°Cfor a low temperature cooling water process (14-16°C), subject to temperate climate ambient conditions and ±0.85°C for a high temperature cooling water process (29-36°C),subject to continental climate ambient conditions.Considering the associated tower cooling loads, predicted results were found to be within a 6% root-mean-square differencecompared to experimental data.
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Medhi Nasrabadi et al.Sensitivity Studies of a Low Temperature Low Approach Direct Cooling Tower for Building Radiant Cooling Systemshttps://arrow.dit.ie/engschmeccon/72
https://arrow.dit.ie/engschmeccon/72Fri, 10 Feb 2017 02:21:05 PST
Recent interest in cooling towers as a mechanism for producing chilled water, together with the evolution of radiant cooling, have prompted a review of evaporative cooling in temperate maritime climates. The thermal efficiency of such systems is a key parameter, as a measure of the degree to which the system has succeeded in exploiting the cooling potential of the ambient air. The feasibility of this concept depends largely however, on achieving low approach water temperatures within an appropriate cooling tower, at acceptable levels of energy performance. Previous experimental work for a full scale evaporative cooling system has shown that it is possible to produce cooling water at low process approach conditions (1-3 K), at the higher temperatures required in radiant and displacement systems (14-18C), with varying levels of annual availability in different temperate climate locations. For such conditions, evaporative cooling has the potential to offer an alternative approach for producing chilled water, particularly in temperate climates, where conventional mechanical air-conditioning systems can, for certain buildings, be considered to be an over engineered solution but where passive cooling is insufficient to offset cooling loads. The current paper describes the development of a mathematical model which analyses the behavior of a low approach open evaporative cooling tower. The model is used to carry out a series of sensitivity studies assessing the performance of the cooling tower subject to various weather and climatic boundary conditions.
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Mehdi Nasrabadi et al.Energy Reduction by Enhanced Evaporative Cooling of Buildings in Martime Climateshttps://arrow.dit.ie/engschmeccon/71
https://arrow.dit.ie/engschmeccon/71Tue, 07 Feb 2017 06:01:11 PST
Direct cooling of buildings by water evaporation has traditionally been seen as appropriate, only, in dry and arid climates, which experience high levels of wet bulb temperature depression. The technique has generally not been applied in maritime climates where low levels of wet bulb temperature depression are frequently found. However, recent developments in enhancing heat and mass transfer in cooling towers, together with the success of high temperature sensible cooling systems, such as chilled ceiling panels and beams, have prompted a review of the evaporative cooling technique as an effective and low energy means of cooling modern deep plan buildings, in maritime climates. At present, however, there is little in depth research and analysis of the performance, energy efficiency, and availability of this form of cooling in maritime conditions. To address these issues an experimental research programme has been established with a view to demonstrating the potential and optimising the design of this form of cooling under low approach conditions. This paper presents the results of recent experimental research into the electrical consumption of a prototype inverter controlled cooling tower when generating cooling water at the chilled water temperatures required for chilled ceiling panels and beams, under varying load and wet bulb temperature approach conditions. Energy consumption efficiencies are presented for a range of specific conditions and typical annual efficiencies are computed. Results are compared with typical energy consumption efficiencies of conventional, vapour compression based, cooling systems. A considerable potential for the reduction of cooling electrical energy consumption, in maritime climates, is shown.
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Ben Costelloe et al.Thermal Performance of Low Approach Evaporative Cooling Systems in Buildingshttps://arrow.dit.ie/engschmeccon/70
https://arrow.dit.ie/engschmeccon/70Mon, 06 Feb 2017 02:31:08 PST
Meteorological enthalpy analysis of temperate and maritime climates above 45˚N suggests that the water-side evaporative cooling technique has considerable unrealised potential with contemporary "high temperature" building cooling systems - such as chilled ceilings. As low approach conditions are the key to exploiting the cooling potential of the ambient air, thermal performance at such conditions needs to be investigated. To address the research issues a test rig, based on an open cooling tower and plate heat exchanger and designed to maximise evaporative cooling potential, has been constructed at DIT. A combination of experimental measurement and analysis is used in the investigations.

The performance of open cooling towers, resulting from experimental research, is usually correlated, as a function of the water and air flow rate, in terms of the cooling tower coefficient, or number of transfer units (NTU) achieved. A new correlation has been developed for the experimental tower, which shows a significant increase in the NTU level, at the lower water to air flow rate ratios of interest. As the cooling tower in this application is predominantly a mass transfer device, the evaluation of the total volumetric heat and mass transfer coefficient (kg/sm3) is of particular interest. This coefficient has been determined for the experimental tower and provides a key parameter for the design of this form of heat dissipation in buildings.

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Ben Costelloe et al.Thermal Efficiency Characteristics of Indirect Evaporative Cooling Systemshttps://arrow.dit.ie/engschmeccon/69
https://arrow.dit.ie/engschmeccon/69Fri, 03 Feb 2017 05:06:06 PST
Recent developments in enhancing heat transfer in cooling towers, together with the success of chilled ceilings, have prompted a review of the evaporative cooling technique. in temperate maritime climates. The thermal efficiency of such systems is a key parameter, as a measure of the degree to which the system has succeeded in exploiting the cooling potential of the ambient air. This paper presents the results of experimental research into the thermal efficiency of a water-side open indirect evaporative cooling test rig designed to achieve low (1-4 K) approach conditions. Secondary efficiencies in the range 0.24-0.76 have been achieved.
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Ben Costelloe et al.A Collagen Based Tissue Engineered Heart Valve Shows Excellent Functionality and Remodelling After Dynamic Conditioninghttps://arrow.dit.ie/engschmeccon/68
https://arrow.dit.ie/engschmeccon/68Fri, 03 Feb 2017 04:51:08 PSTClaire Brougham et al.Energy Performance of Indirect Evaporative Cooling in Chilled Ceiling Applications in Maritime Temperate Climateshttps://arrow.dit.ie/engschmeccon/67
https://arrow.dit.ie/engschmeccon/67Fri, 03 Feb 2017 04:51:03 PST
Evaporative cooling has had limited application in maritime, temperate, climates due to the low levels of cooling water availability which result, when low temperature (5 to 8˚C), convection based, building cooling systems are used. However, the success of "high temperature" radiant cooling, in the form of chilled ceilings, has prompted a review of evaporative cooling in maritime, temperate, conditions. In order to maximize evaporative cooling availability, however, in this application, it is necessary to achieve low wet bulb temperature approach conditions, at viable levels of primary energy consumption. This paper presents the results of experimental research into the energy performance of an evaporative cooling test rig, designed to maximize cooling water availability at the temperatures required for chilled ceilings (14 to 18°C). Results are compared with typical energy efficiencies of conventional, refrigeration based, building cooling systems. A significant potential for improved energy performance, is shown.
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Ben Costelloe et al.Evaporative Cooling Availability in Water Based Sensible Cooling Systemshttps://arrow.dit.ie/engschmeccon/66
https://arrow.dit.ie/engschmeccon/66Thu, 02 Feb 2017 09:03:09 PST
Recent developments have prompted a review of evaporative cooling technology as an effective means of cooling modern deep plan buildings. Prominent among these developments is the success of high temperature sensible cooling systems, such as chilled ceilings, which require a supply of cooling water at 14 to 18°C. Crucial to the success of evaporative cooling technology, as a significant means of cooling in modern applications, is the ability to generate cooling water, in an indirect circuit, at a temperature which closely approaches the ambient adiabatic saturation temperature or wet bulb temperature. Recent research in this area has shown that it is feasible to generate such cooling water at a temperature of 3 K above the ambient adiabatic saturation temperature.

While the frequency of ambient adiabatic saturation temperature occurrence can be obtained from meteorological sources, there is little published data and analysis on the potential for this form of cooling water generation, based on the approach temperatures which are now known to be feasible. This paper quantifies cooling availability for two European cities, Dublin and Milan and suggests a method of analysing such data for any world wide location for which suitable meteorological records are available. The paper, which is part of an ongoing research programme devoted to evaporative cooling, incorporates recent experimental research findings and bases the availability analysis on meteorological test reference weather year data, which has been published for 29 European locations.

The results of this research confirm a major potential for the generation of cooling water by evaporative means, which can be used to provide effective cooling of modern deep plan buildings by means of contemporary water based sensible cooling systems, such as chilled ceiling panels and beams. While the technique offers most potential in locations with a Northern European temperate climate, it seems to have a significant potential to contribute to cooling in Southern European cities, during the non-Summer months and also at other times, particularly where load shaving and night time cooling and pre-cooling techniques are incorporated.

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Ben Costelloe et al.The Design and Performance of an Evaporative Cooling Test Rig for a Maritime Climatehttps://arrow.dit.ie/engschmeccon/65
https://arrow.dit.ie/engschmeccon/65Tue, 31 Jan 2017 00:51:03 PST
Recent developments have prompted a review of the use of cooling tower based evaporative cooling technology as an effective means of cooling modern buildings. Prominent among these developments is the success of high temperature cooling systems such as radiant ceiling panels and chilled beams. At present, however, there is little published literature which gives a quantitative, in depth analysis of the performance or energy efficiency of cooling towers, used in maritime climates, in conjunction with heat exchangers and run at low approach and low wet bulb temperatures throughout the free cooling season. This lack of knowledge has meant that many current opportunities to benefit from the technology are not availed of by building design teams. To address this issue an automated laboratory test rig has been specifically developed with the aim of optimising the performance and demonstrating the potential of this form of cooling in maritime conditions. This paper, which reports on work in progress, describes the design and development of the rig and presents and analyses the preliminary test results.
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Ben Costelloe et al.The Feasibility of Utilising Compressed Natural Gas as Part of a Systematic Approach to Establishing the Necessary Groundwork for the Hydrogen Based Transport Economyhttps://arrow.dit.ie/engschmeccon/64
https://arrow.dit.ie/engschmeccon/64Wed, 09 Nov 2016 09:24:14 PST
One key objective for vehicle manufacturers is to develop technology and infrastructure to facilitate the progression from combustion to conversion by the year 2050. In the short to medium term however, the combustion of fossil fuels such as petrol and diesel, coupled with advanced transmission innovations and emission control technology that are governed by strict Euro VI regulations appears to be the main path forward for the transport sector and the environment. This paper presents the feasibility of utilising the developing compressed natural gas network capabilities as part of a systematic approach to establishing the necessary groundwork for a hydrogen based transport economy. Results of tests conducted by Dublin Institute of Technology to evaluate natural gas engine performance and exhaust emissions compared with conventional fossil fuelled engines were examined. The paper also outlines Gas Networks Ireland’s vision for the future of transport and the use of compressed natural gas as a fuel alternative for the transport sector. The barriers to implementing a strategic plan for gas fuel for the transport sector are also reviewed. This includes the public’s perception of gas as a transport fuel, on-board storage of gas, related weight and extreme pressure issues, range limitations, dual fuel operation, gas quality and the necessary fuelling infrastructure. By resolving some of these problems, the transition to a hydrogen based economy for transportation purposes may prove feasible by 2050.
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James Brunton et al.A Comparative Study of Zn-Mn Electrodeposition From Deep Eutectic Solvents and Aqueous Electrolyteshttps://arrow.dit.ie/engschmeccon/63
https://arrow.dit.ie/engschmeccon/63Wed, 04 May 2016 08:56:44 PDT
The production of Zn-Mn coatings with high Mn and low oxygen content from additive free choline chloride/urea deep eutectic solvent (DES) is reported in this work. Alloy coatings containing high Mn contents (~30 at.% Mn) show the highest corrosion resistance amongst zinc alloys [1]. However, in order to obtain Mn-rich deposits on steel from a simple aqueous bath, a significant cathodic polarization or high deposition current density is necessary. Under such conditions, the Zn 2+ reduction reaction is under diffusion control, leading to the formation and growth of dendrites. In addition intensive hydrogen evolution significantly reduces the current efficiency, often leading to the formation of porous coatings containing large amounts of oxygen [2]. It has been shown that a dendritic deposit formation and hydrogen reduction during Zn-Mn electrodeposition at high current densities could be prevented through use of plating additives [3]. By utilising DES instead of an aqueous electrolyte Zn-Mn codeposition was successfully achieved, with deposits containing high amounts of Mn at high current efficiencies. The amount of oxygen present in the alloy deposits obtained from DES was significantly reduced in comparison to those prepared from a normal water based electrolyte. Microstructural features and corrosion stability of the DES Zn-Mn deposits are compared with the coatings deposited from a conventional water-based electrolyte. The quantity of water absorbed from the atmosphere in the DES during both the electroplating procedure and throughout the DES storage period is also reported.
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Jelena Bajat et al.Modification of Luas heating and ventilation systems to reduce energy consumptionhttps://arrow.dit.ie/engschmeccon/62
https://arrow.dit.ie/engschmeccon/62Mon, 02 Nov 2015 09:55:59 PST
Luas is a state of the art light rail system operating in Dublin Ireland. Being electrically powered, energy is a major operating cost for Luas. One component of rolling stock identified by this research that consumes a disproportional amount of energy is that of the heating and ventilation systems. The heating and ventilation systems fitted to Luas vehicles consume as much as 60% of total vehicle power, and under certain conditions can consume more than that of the traction motors. This paper explores solutions to reducing the energy consumption of Luas heating and ventilation systems. The identified software modifications and hardware installations proposed by this research have been estimated to save over 1,400,000 kWh, 7% of total Luas energy consumption. Based on the current average industry price of €0.12 per kWh, this saving equates to almost €170,000 per year.

Transport systems are not immune to the economic downturn seen throughout the Europe Union. With decreasing passenger numbers, operators are faced with reduced revenue streams, which could lead to reduced services or possible job losses. To avoid such action, operators must reduce their operating costs adequately. Heating and ventilation systems provide passengers with a controlled, fresh, temperature-regulated air supply to ensure maximum comfort. Light rail systems are arguably one of the most difficult transport modes in which to regulate air temperature and quality, due to their short trip distances with a high number of stops.

Each Luas vehicle has three heating and ventilation units. The total rated power of the three systems is 60 kW, power is supplied by way of 750 V DC direct from the overhead catenary supply. Each unit is controlled by a self-contained control unit where in all eventualities, the system endeavours to achieve a variable interior set point between 14 °C and 20 °C. The system is set up to automatically start once the vehicle is prepared (switched on) and will remain on (temperature depending) until the vehicle is de-prepped (switched off).

Testing of the system, recorded a maximum consumption of 60 kWh at an operating temperature of 2 °C. Contrastingly a test conducted at 19 °C the consumption was 3 kWh. Detailed analysis of Luas operations indicates that on average 30% of the time Luas trams are in operation, is not actual passenger service. However the heating and ventilation systems are operational during these periods. Automatically disabling the systems during these non-passenger periods would reduce energy consumption significantly, while not adversely affecting passenger comfort.

To achieve this objective, three modifications have been identified. The first two will automatically disable the heating and ventilation system while operating in periods of non-passenger service when the vehicle is in traction and while the vehicle is stable in the shunt (end of line). The third modification will reduce the set point profile, the system endeavours to reach. The paper describes in detail the software modifications and hardware installations required to roll out these modifications across the Luas fleet.

The aim of this project was to design and develop a group pump and solve associated technical issues for a construction company in Ireland. The design is based on a high shear colloidal group mixing and pumping rig. The initial machine has failed in terms of bearing and seal performance, has high manufacturing costs and is poorly designed.

To account for these issues, extensive research of the design features of grout mixing units from various competitors and suppliers was carried out by research and field studies at trade fairs. Using the information gathered, and incorporating improvements into the existing design, a test rig was developed and tested. Performance tests consisted of varying the flow rates of the grout material through specified industrial flow rate ranges. The head loss through the system was plotted against flow rate to obtain system design curves. Design calculations were used to size the hydraulic motor, the impeller shaft diameter, dynamic loading on bearings and their operational lifetime. The result of the performance testing indicated that the machine performance met specifications. The new colloidal mixing unit met grout mixing standards for a water/cement ratio of 0.4. This was validated with flow cone testing. The dual bearing system design proved satisfactory, with smooth operation even at higher ranges of industrial flow rates. The mechanical seals were selected for aggressive environments and the seal system developed for the grout pump remained leak proof, as designed. The original machine’s was smooth and provided high quality batches of grout. The new pump design features includes a widened pumping impeller for increased shearing of the group and gives higher volumetric flow rates. This offers enhanced mixing attributes while retaining the positive aspects of the original design such as vortex mixing, high shear colloidal mixing and portability.

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John Kijak et al.Feedback Dynamics in the Academic and Industrial Environmenthttps://arrow.dit.ie/engschmeccon/59
https://arrow.dit.ie/engschmeccon/59Mon, 11 Mar 2013 09:05:51 PDT
Feedback is essential in all companies, in society and in educational environments. We learn, improve and develop from it in our examinations, group work, work environment and relationships. Feedback however must be supported with good communications and be consistent. In the classroom environment this means providing feedback in a positive and supportive manner, and being consistent to all. Most if not all managers and leaders, including lecturers have not undertaken any form of training in feedback methods and therefore it is not translated effectively, causing stress or misguidance to students and colleagues. This paper highlights the importance of good feedback, how it can be provided effectively and why it is rarely communicated. Students are consistently asking for feedback and highlight it in quality reports and surveys as a major weakness in the delivery of modules and course work. Some of the issues raised are associated with poor preparation, habits and styles of delivery. With the increasing requirement from Validation and Accreditation authorities to verify if learners are receiving appropriate feedback, this is one area where staff and managers can enhance the quality of the learning environment. Feedback is not only a two way process between lecturers and students but is also a critical activity between management and staff in developing a healthy working environment. Relevant feedback to first year students in particular via verbal or electronic means sets the standard for subsequent years. It is also essential that the quality work undertaken by lecturers to students is acknowledged and supported by management.
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David Kennedy et al.Improving Core Skills in Apprentice Educationhttps://arrow.dit.ie/engschmeccon/58
https://arrow.dit.ie/engschmeccon/58Fri, 22 Feb 2013 08:25:49 PST
Many Motor trade apprentice students enter the later years of their studies ill prepared for the level of the material encountered. This is due to several factors including the level of mathematics they have on leaving school. A lot of basic material has been covered during earlier years of their training but by the time they reach the third year of their apprenticeship (Phase 6) it is not safe to assume that they have a full grasp of the basics required. I have developed a diagnostic test to measure the level of preparedness of these students. This test covers basic mathematics, science and engine technology.

In addition to this the diagnostic test also forces students to revise and master the basics from their earlier years. Along with the test a series of online resources have also been provided to the students.

In this paper the test is outlined in detail. We enumerate the problem areas encountered by students studying mathematics and related subjects and suggest possible improvements that could be made by this initiative.

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Peter KennyImproving Core Mathematical Skills in Motor Apprentice Education in Irelandhttps://arrow.dit.ie/engschmeccon/57
https://arrow.dit.ie/engschmeccon/57Fri, 22 Feb 2013 08:25:48 PST
In order to enter into an apprenticeship in Ireland a qualification in mathematics is not essential. Throughout their apprenticeship many motor trade apprentices find that many past mathematical weakness resurface. In addition to this the level and standard of mathematics increases as apprentices progress through their training.

A maths diagnostic test has been developed and sat by a selection of Motor Mechanic apprentices attending off the job training at the Dublin Institute of Technology during the 2011 to 2012 academic year.

The results of this test indicate that many students experience difficulty with mathematically related subjects. The test was then repeated by the same students mid way through the course in order to review their progress. In the intervening period students were encouraged to study a series of online resources. A full statistical analysis and discussion of the results is presented here.

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Peter KennyDiagnosing Weakness in Basic Principles of Electricity in Motor Apprentice Education in Irelandhttps://arrow.dit.ie/engschmeccon/56
https://arrow.dit.ie/engschmeccon/56Fri, 22 Feb 2013 08:25:47 PST
Many Motor trade apprentice students enter the later years of their studies ill prepared for the level of material encountered. This is due to several factors including the level and knowledge of basic electricity and electrical/electronic principles.

A lot of basic material in these areas has been covered during earlier years of their training but by the time they reach the final year of their apprenticeship (Phase 6) it is not safe to assume that they have a full grasp of the basics required.

We have developed a diagnostic test to measure the level of preparedness of these students. This test covers basic electricity and electrical/electronic principles associated with motor vehicle technology.

In addition to this primary diagnostic test a series of online tests have been devised that force students to revise and master the basics from their earlier years. In addition to these tests a series of online resources have also been provided to assist students.

In this paper the test is outlined in detail. We enumerate the problem areas for the students and list the improvements that have been made by this initiative.

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Peter KennyProcess Refinement Through Design of Experiments (Taguchi) to Reduce Porosity Levels of Thin Flame Spray NiCrBSi Coatings on Cast Aluminium Alloyshttps://arrow.dit.ie/engschmeccon/55
https://arrow.dit.ie/engschmeccon/55Wed, 26 Sep 2012 01:48:55 PDT
Thin(16matrix of key deposition parameters was constructed to develop the optimum spray parameters. The effects of parameter variations on the porosity levels of these coatings were assessed. Key parameter interactions were reported. Quantifiable interactions between the selected parameters were noted for the LM24 substrate. However, on the LM25 substrate these interactions were much less defined. Corrosion performance of the optimised coatings, based on electrochemical impedance spectroscopy, was reported. The presence of through-pores in the coatings were shown to reduce the corrosion resistance of the coated systems by a factor of 10, in dilute NaCl solutions, compared to bulk 316L stainless steel.
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David Culliton et al.